The present invention relates to gas lasers and more particularly to a waveguide laser having a gain medium excited by a capacitively coupled discharge.
Laser systems having a gain medium including halide and rare gas elements and utilizing direct electrical discharge excitation are capable of providing output beams having radiation with wavelengths in the ultraviolet and/or visible spectrum. Wang et al. in U.S. Pat. No. 4,039,971 filed May 4, 1976 discloses a fast discharge, high power, electric discharge pumped gas laser. The laser includes a Blumlein-type discharge device employing a pair of coplanar conductor plates with linear spaced apart confronting edges constituting the anode and cathode electrodes of the discharge device with the lasing gas occupying the volume of the gas between the electrodes. Additionally, Burnham et al., in "Applied Physics Letters", Volume 29, No. 1, July 1, 1976 discloses an electric discharge laser having a xenon fluoride or krypton fluoride gain medium. The laser action was obtained in the xenon fluoride and krypton fluoride in a transverse electric discharge powered by a fast Blumlein-type circuit. The laser employed parallel plate electrodes and the lasing gas was excited by capacitive discharge between the electrodes.
In prior art devices the maximum power output and/or pulse repetition rates are limited by the temperature rise in the gain medium during operation. High power and/or high pulse rate operation requires that the gain medium efficiently transfer heat, generated by the discharge, out of the gain medium. Typically, this is accomplished by providing a coolant to extract heat from the gain medium, by circulating the gain medium through a heat exchanger or by flowing the gain medium through the optical cavity in a single pass system.
The utilization of a waveguide optical cavity such as disclosed by Schlossberg in United States Patent 4,103,255 allows the laser to be operated with a small diameter discharge thereby reducing the size of the laser and the power required to sustain lasing action. Additionally, a waveguide laser enables operation with a gain medium at high pressure.